Thermal crosslink material, manufacture method of liquid crystal display panel and liquid crystal display panel

ABSTRACT

Disclosed are a thermal crosslink material, a manufacture method of a liquid crystal display panel, and a liquid crystal display panel. A structural formula of the thermal crosslink material is 
     
       
         
         
             
             
         
       
     
     wherein A is 
     
       
         
         
             
             
         
       
     
     B is 
     
       
         
         
             
             
         
       
     
     and R is a linear or chain branched alkyl having 5-20 C atoms, wherein one or more CH 2  in the alkyl is substituted with phenyl cycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or one or more H atoms in the first group are substituted with F atom or Cl atom; a specific crosslink material may be one of 
     
       
         
         
             
             
         
       
     
     Molecules of the thermal crosslink material crosslink together to form a polymer having a crosslinked network, and groups A and B can be anchored on a substrate surface. The branch R provides an effect of vertical alignment and can form alignment films.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of co-pending U.S. patent applicationSer. No. 15/026,255, filed on Mar. 31, 2016, which is a national stageof PCT Application No. PCT/CN2016/074615, filed on Feb. 26, 2016,claiming foreign priority of Chinese Patent Application No.201610070586.8, filed on Jan. 29, 2016.

FIELD OF THE INVENTION

The present invention relates to a display manufacture field, and moreparticularly to thermal crosslink material, a manufacture method of aliquid crystal display panel and a liquid crystal display panel.

BACKGROUND OF THE INVENTION

The TFT-LCD (Thin Film Transistor Liquid Crystal Display) possessesadvantages of thin body, power saving and no radiation to be widely usedin many application scopes. Most of the TFT-LCDs on the present marketare back light type liquid crystal displays, which comprise a liquidcrystal display panel and a back light module. The working principle ofthe liquid crystal display panel is to locate liquid crystal moleculesbetween two parallel glass substrates. The light of back light module isreflected to generate images by applying driving voltages to controlwhether the liquid crystal molecules to be changed directions.

Generally, the liquid crystal display panel comprises a CF (ColorFilter) substrate, a TFT (Thin Film Transistor) substrate, LC (LiquidCrystal) sandwiched between the CF substrate and TFT substrate andsealant. The formation process generally comprises: a forepart Arrayprocess (thin film, photo, etching and stripping), a middle Cell process(Lamination of the TFT substrate and the CF substrate) and a post moduleassembly process (Attachment of the driving IC and the printed circuitboard). The forepart Array process is mainly to form the TFT substratefor controlling the movement of the liquid crystal molecules; the middleCell process is mainly to add liquid crystal between the TFT substrateand the CF substrate; the post module assembly process is mainly thedriving IC attachment and the integration of the printed circuit board.Thus, the liquid crystal molecules are driven to rotate and displaypictures.

In the liquid crystal display panel, a layer of alignment film is formedon the thin film transistor substrate and a color film substrate ingenerally. After the alignment film contacts with the LC, it can makethe LC have a pre-tilted angle in certain direction, and thus provide aloading angle (the pre-tilted angle has significant influence to thedriving voltage, contrast, response time and view angle of the TFT-LCD)for the liquid crystal molecules. Polyimide (PI) is commonly chosen tobe the material of the alignment film, which mainly has rubbingalignment type IP material and lighting alignment type IP material.However, either of the alignment materials has its own drawback. Therubbing alignment type IP material is to form the alignment film withRubbing method. The Rubbing method is to use fabric roller to performcontacting directional mechanical friction on the macromolecular PI filmsurface. The energy provided by rubbing the macromolecular surface makethe macromolecular main chain be aligned in direction due to theextension, and thus the interaction of the branch and the LC iscontrolled to align the LC in the direction of the pre-tilted angle; asrubbing, the issues of powder particles, residual electrostatic andbrush marks reduce the process yield. The lighting alignment type IPmaterial is to form the alignment film with photo-alignment technology.The photo-alignment technology is to utilize the photochemical reactionof the ultraviolet light polymer monomers to create the anisotropy, andthe liquid crystal molecules and the alignment film surface branchinteract with each other. For reaching the stable status of the minimumenergy, the liquid crystal molecules are aligned along the direction ofwhich the acted force is the maximum defined by the lighting alignment.The lighting alignment type IP material can solve the aforesaid problemsbut with the restriction of the material properties, the heat resistanceand the aging resistance are poor, and meanwhile, the LC anchoringability is weaker, the quality of the panel is influenced. Besides, thePI material itself has high polarity and high water absorption. Thestorage and the delivery can easily change the property to result in thenonuniform alignment. The price of the PI material is expensive, and thefilm formation process on the TFT-LCD is more complicated, which leadsto the increase of the panel cost.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide thermal crosslinkmaterial, employed to form the alignment films to reduce the productioncost of the alignment films and promote the capacity.

Another objective of the present invention is to provide a manufacturemethod of a liquid crystal display panel, in which by adding the thermalcrosslink material in the liquid crystal compound of the liquid crystaldisplay panel to form the alignment films on the surfaces of oppositesides of the TFT substrate and the CF substrate to simplify themanufacture process and to reduce the production cost.

Another objective of the present invention is to provide a liquidcrystal display panel, in which the alignment films are polymer, whichis formed by that the thermal crosslink material mixed in the liquidcrystal material is generated with the crosslinking reaction in aheating condition, and is deposed on the surfaces of opposite sides ofthe TFT substrate and the color film substrate, and the manufactureprocess is simple, and the production cost is low.

For realizing the aforesaid objectives, the present invention providesthermal crosslink material, employed to be alignment film material, anda structural formula thereof is

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH2 group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or CI atom.

A structural formula of thermal crosslink material is:

The present invention further provides a manufacture method of a liquidcrystal display panel, comprising steps of:

step 1, mixing thermal crosslink material into liquid crystal materialto obtain liquid crystal compound;

a structural formula of the thermal crosslink material is

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom;

step 2, providing a TFT substrate, and employing one drop filling todrop the liquid crystal compound obtained in the step 1 on one side ofthe TFT substrate;

step 3, providing a CF substrate, and employing one drop filling to dropseal on one side of the CF substrate to form a sealant;

step 4, oppositely vacuum laminating the TFT substrate and the CFsubstrate, and then the sealant and the liquid crystal compound arepositioned between the TFT substrate and the CF substrate to obtain acell;

step 5, irradiating the cell obtained in the step 4 with ultravioletlight, and then heating the same to cure the sealant, and in the heatingprocess, the thermal crosslink material in the liquid crystal compoundgenerates crosslinking reaction to form polymer, and with increase ofpolymer molecular weight, the polymer generates phase separation withthe liquid crystal material to be deposed on the surfaces of oppositesides of the TFT substrate and the CF substrate to form the alignmentfilms, wherein the branch part R in the polymer which is compatible withthe liquid crystal acts a result of vertical alignment.

A structural formula of the thermal crosslink material is:

In the liquid crystal compound obtained in the step 1, a content of thethermal crosslink material is 0.1-5 wt %.

In the step 5, an irradiation intensity of the ultraviolet light is50-100 mW/cm², and an irradiation period is 1-5 min, and a heatingtemperature is 110-130° C., and a heating period is 20-30 min.

The liquid crystal display panel is a multi-domain vertical alignmenttype liquid crystal display panel, and a plurality of roof shapeprojections are provided on the one side of the TFT substrate providedin the step 2 where the liquid crystal compound is pre-dropped, and aplurality of roof shape projections are provided on the one side of theCF substrate provided in the step 3 where the sealant is pre-dropped.

Pixel electrodes are provided on the one side of the TFT substrateprovided in the step 2 where the liquid crystal compound is pre-dropped,and a common electrode is provided on the one side of the CF substrateprovided in the step 3 where the sealant is pre-dropped.

The present invention further provides a liquid crystal display panel,comprising a TFT substrate and a CF substrate which are oppositelypositioned, and a liquid crystal layer sandwiched between the TFTsubstrate and the CF substrate, a sealant employed for sealing the TFTsubstrate and the CF substrate, and alignment films formed at surfacesof the TFT substrate and the CF substrate facing the liquid crystallayer;

a plurality of roof shape projections are provided on sides of the TFTsubstrate and the CF substrate facing the liquid crystal layer;

the liquid crystal layer comprises liquid crystal material;

the alignment films are polymer, which is formed by that the thermalcrosslink material mixed in the liquid crystal material is generatedwith the crosslinking reaction in a heating condition, and is deposed onthe surfaces of opposite sides of the TFT substrate and the CFsubstrate;

a structural formula of the thermal crosslink material is

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom.

A structural formula of the thermal crosslink material is:

The benefits of the present invention are: the present inventionprovides thermal crosslink material, a manufacture method of a liquidcrystal display panel and a liquid crystal display panel; a structuralformula of the thermal crosslink material according to the presentinvention is

wherein A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom; the thermal crosslink materialbelongs to an organic material of Methacrylic acid, and in a heatingcondition, the crosslinking reaction can be generated among themolecules to form macromolecular polymer having crosslinked network, andafter mixing the thermal crosslink material in the liquid crystalmaterial to be heated to form the polymer, the head groups A and B canbe anchored on the substrate surface after the phase separation, and thebranch R can act the result of vertical alignment, and thus to form thealignment films. Consequently, the manufacture cost of the TFT-LCD canbe reduced and the capacity can be promoted; in the manufacture of theliquid crystal display panel according to the present invention, byadding the thermal crosslink material in the liquid crystal compound ofthe liquid crystal display panel to form the alignment films on thesurfaces of opposite sides of the TFT substrate and the CF substrate tosimplify the manufacture process and to reduce the production cost.Besides, the crosslinking reaction can be generated among the moleculesof the thermal crosslink material in the heating condition. Incomparison with the PSVA type display panel, the additional ReactiveMonomer (RM) is not necessary, and one ultraviolet light irradiationprocess can be omitted; in the liquid crystal display panel of thepresent invention, the alignment films are polymer, which is formed bythat the thermal crosslink material mixed in the liquid crystal materialis generated with the crosslinking reaction in a heating condition, andis deposed on the surfaces of opposite sides of the TFT substrate andthe color film substrate. Then, the PI alignment films can beeliminated, and the manufacture process of the TFT-LCD can be simplifiedto significantly reduce the manufacture cost of the TFT-LCD, and thealignment result of the liquid crystal is great.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the characteristics and technical aspectof the invention, please refer to the following detailed description ofthe present invention is concerned with the diagrams, however, providereference to the accompanying drawings and description only and is notintended to be limiting of the invention.

In drawings,

FIG. 1 is a structure diagram of thermal crosslink material according tothe present invention;

FIG. 2 is a structure diagram of polymer formed by that the thermalcrosslink material of the present invention is heated and generated withthe crosslinking reaction;

FIG. 3 is a flowchart of a manufacture method of a liquid crystaldisplay panel according to the present invention;

FIG. 4 is a diagram of step 4 in the manufacture method of the liquidcrystal display panel according to the present invention;

FIG. 5 is a diagram of step 5 in the manufacture method of the liquidcrystal display panel according to the present invention, and a liquidcrystal distribution diagram of the liquid crystal display panel of thepresent invention without being applied with power;

FIG. 6 is a liquid crystal distribution diagram of the liquid crystaldisplay panel of the present invention with being applied with power;

FIG. 7 is a nuclear magnetic resonance data analysis diagram of themanufactured thermal crosslink material of the specific structure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For better explaining the technical solution and the effect of thepresent invention, the present invention will be further described indetail with the accompanying drawings and the specific embodiments.

The present invention first provides thermal crosslink material,employed to be alignment film material, and a structural formula thereofis

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom.

Specifically, as shown in FIG. 1, in the thermal crosslink material, theA and the B belongs to the head group, and the head group comprises twoor more double bond groups. The main function thereof is to generatethermal crosslink reaction at the certain temperature; the main functionof the tail group R is similar to the function of the PI branch tovertically align the liquid crystal molecules in the steric hindrancemanner.

Preferably, a structural formula of the thermal crosslink material is:

The thermal crosslink material provided by the present invention belongsto an organic material of Methacrylic acid. As shown in FIG. 2, in aheating condition, the crosslinking reaction can be generated among themolecules to form macromolecular polymer having crosslinked network.Then, after mixing the thermal crosslink material in the liquid crystalmaterial to be heated to form the polymer, the head groups A and B canbe anchored on the substrate surface after the phase separation, and thebranch R can act the result of vertical alignment, and thus to form thealignment films. Consequently, the liquid crystal display panelutilizing the thermal crosslink material can eliminate the PI alignmentfilms. The manufacture process of the TFT-LCD can be simplified tosignificantly reduce the manufacture cost of the TFT-LCD.

Please refer to FIG. 3, the present invention further provides amanufacture method of a liquid crystal display panel, comprising stepsof:

step 1, mixing thermal crosslink material 51 into liquid crystalmaterial 52 to obtain liquid crystal compound;

a structural formula of the thermal crosslink material 51 is

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom;

Preferably, a structural formula of the thermal crosslink material 51is:

Specifically, in the liquid crystal compound obtained in the step 1, acontent of the thermal crosslink material 51 is 0.1-5 wt %.

step 2, providing a TFT substrate 10, and employing one drop filling(ODF) to drop the liquid crystal compound obtained in the step 1 on oneside of the TFT substrate 10;

step 3, providing a CF substrate 20, and employing one drop filling todrop seal on one side of the CF substrate 20 to form a sealant 30;

step 4, as shown in FIG. 4, oppositely vacuum laminating the TFTsubstrate 10 and the CF substrate 20, and then the sealant 30 and theliquid crystal compound are positioned between the TFT substrate 10 andthe CF substrate 20 to obtain a cell;

then, the thermal crosslink material 51 is still mixed in the liquidcrystal material 52, and the crosslinking reaction has not generated,and has not acted alignment function to the liquid crystal material 52.

step 5, as shown in FIG. 5, irradiating the cell obtained in the step 4with ultraviolet light, and then heating the same to cure the sealant30, and in the heating process, the thermal crosslink material 51 in theliquid crystal compound generates crosslinking reaction to form polymer,and with increase of polymer molecular weight, the polymer generatesphase separation with the liquid crystal material 52 to be deposed onthe surfaces of opposite sides of the TFT substrate 10 and the CFsubstrate 20 to form the alignment films 50, wherein the branch part Rin the polymer which is compatible with the liquid crystal acts a resultof vertical alignment.

Specifically, in the step 5, an irradiation intensity of the ultravioletlight is 50-100 mW/cm², and an irradiation period is 1-5 min, and aheating temperature is 110-130° C., and a heating period is 20-30 min.

Specifically, the liquid crystal display panel is a multi-domainvertical alignment (MVA) type liquid crystal display panel, and the TFTsubstrate provided in the step 2 is a TFT substrate of the traditionalMVA type liquid crystal display panel, and a plurality of roof shapeprojections 21 are provided on the one side of the TFT substrate wherethe liquid crystal compound is pre-dropped, and the CF substrateprovided in the step 3 is a CF substrate of the traditional MVA typeliquid crystal display panel, and a plurality of roof shape projections21 are provided on the one side of the CF substrate where the sealant ispre-dropped.

Specifically, pixel electrodes are provided on the one side of the TFTsubstrate provided in the step 2 where the liquid crystal compound ispre-dropped, and a common electrode is provided on the one side of theCF substrate provided in the step 3 where the sealant is pre-dropped. Asshown in FIG. 6, by applying voltages to the pixel electrodes on the TFTsubstrate and the common electrode on the CF substrate of themanufactured liquid crystal display panel, the liquid crystal material52 are acted by the common function of the projections 21 and thealignment films 50 to be aligned according to the slope inclination ofthe projections 21.

In the manufacture of the liquid crystal display panel according to thepresent invention, by adding the thermal crosslink material in theliquid crystal compound of the liquid crystal display panel to form thealignment films on the surfaces of opposite sides of the TFT substrateand the CF substrate to simplify the manufacture process and to reducethe production cost. Besides, the crosslinking reaction can be generatedamong the molecules of the thermal crosslink material in the heatingcondition. In comparison with the PSVA type display panel, theadditional Reactive Monomer (RM) is not necessary, and one ultravioletlight irradiation process can be omitted.

Please refer to FIGS. 5-6, the present invention further provides aliquid crystal display panel, comprising a TFT substrate 10 and a CFsubstrate 20 which are oppositely positioned, and a liquid crystal layersandwiched between the TFT substrate 10 and the CF substrate 20, asealant 30 employed for sealing the TFT substrate 10 and the CFsubstrate 20, and alignment films 50 formed at surfaces of the TFTsubstrate 10 and the CF substrate 20 facing the liquid crystal layer;

a plurality of roof shape projections 21 are provided on sides of theTFT substrate 10 and the CF substrate 20 facing the liquid crystallayer;

the liquid crystal layer comprises liquid crystal material 52;

the alignment films 50 are polymer, which is formed by that the thermalcrosslink material 51 in the liquid crystal material 52 is generatedwith the crosslinking reaction in a heating condition, and is deposed onthe surfaces of opposite sides of the TFT substrate 10 and the CFsubstrate 20;

a structural formula of the thermal crosslink material 51 is

wherein

A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH2 group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or CI atom.

Preferably, a structural formula of the thermal crosslink material 51is:

Specifically, the pixel electrodes and the common electrode arerespectively provided on opposite sides of the TFT substrate 10 and theCF substrate 20. As shown in FIG. 5, in condition that the voltage isnot applied to the liquid crystal display panel, the liquid crystalmaterial 52 is acted by the function of the alignment films 50 to bevertically aligned. As shown in FIG. 6, by applying voltages to thepixel electrodes 10 on the TFT substrate and the common electrode 20 onthe CF substrate of the manufactured liquid crystal display panel, theliquid crystal material 52 are acted by the common function of theprojections 21 and the alignment films 50 to be aligned according to theslope inclination of the projections 21.

A manufacture method of thermal crosslink material of the specificstructure is shown in the following specific embodiment:

the manufacture method of the thermal crosslink

material

is:

weighting and measuring the glycol compound (I) and the acrylic acid(II) according to the mole ratio of glycol compound (I): the acrylicacid (II) =1:1.5-2, and putting the prepared glycol compound (I) andacrylic acid (II) in the reactor, and then using the sulfuric acidsolution of mass fraction 85-90% to be the catalytic agent to react 4-6hours at 100-130° C. to obtain the compound (III);

The reaction formula of the aforesaid reaction is below:

executing the nuclear magnetic resonance analysis to the obtainedcompound (III), and the obtained nuclear magnetic resonance data is:δ=0.96(3H), δ=1.33(2H), δ=1.62(2H), δ=2.55(2H), δ=7.18(4H), δ=7.43(4H),δ=7.54(4H), δ=2.51(2H), δ=3.06(1H), δ=4.11(4H), δ=1.93(6H), δ=6.15(2H),δ=5.58(2H);

as shown in FIG. 7, thus, it can be ensured that the structural formulaof the compound (III) is

In conclusion, the present invention provides thermal crosslinkmaterial, a manufacture method of a liquid crystal display panel and aliquid crystal display panel; a structural formula of the thermalcrosslink material according to the present invention is

wherein A is

B is

R is a linear or chain branched alkyl having 5-20 C atoms, and a firstgroup obtained after some CH₂ group in the alkyl is replaced by phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or asecond group obtained after the alkyl and some H atom in the first groupare replaced by F atom or Cl atom; the thermal crosslink materialbelongs to an organic material of Methacrylic acid, and in a heatingcondition, the crosslinking reaction can be generated among themolecules to form macromolecular polymer having crosslinked network, andafter mixing the thermal crosslink material in the liquid crystalmaterial to be heated to form the polymer, the head groups A and B canbe anchored on the substrate surface after the phase separation, and thebranch R can act the result of vertical alignment, and thus to form thealignment films. Consequently, the manufacture cost of the TFT-LCD canbe reduced and the capacity can be promoted; in the manufacture of theliquid crystal display panel according to the present invention, byadding the thermal crosslink material in the liquid crystal compound ofthe liquid crystal display panel to form the alignment films on thesurfaces of opposite sides of the TFT substrate and the CF substrate tosimplify the manufacture process and to reduce the production cost.Besides, the crosslinking reaction can be generated among the moleculesof the thermal crosslink material in the heating condition. Incomparison with the PSVA type display panel, the additional ReactiveMonomer (RM) is not necessary, and one ultraviolet light irradiationprocess can be omitted; in the liquid crystal display panel of thepresent invention, the alignment films are polymer, which is formed bythat the thermal crosslink material mixed in the liquid crystal materialis generated with the crosslinking reaction in a heating condition, andis deposed on the surfaces of opposite sides of the TFT substrate andthe color film substrate. Then, the PI alignment films can beeliminated, and the manufacture process of the TFT-LCD can be simplifiedto significantly reduce the manufacture cost of the TFT-LCD, and thealignment result of the liquid crystal is great.

Above are only specific embodiments of the present invention, the scopeof the present invention is not limited to this, and to any persons whoare skilled in the art, change or replacement which is easily derivedshould be covered by the protected scope of the invention. Thus, theprotected scope of the invention should go by the subject claims.

What is claimed is:
 1. A thermal crosslink material, which is employedas an alignment film material, the thermal crosslink material beingrepresented by

where A is

B is

and R is a linear or chain branched alkyl having 5 to 20 carbon atoms,wherein one or more CH₂ group in the alkyl is substituted with phenylcycloalkyl, —O—, —CONH—, —COO—, —O—CO—, —CO—, or —CH═CH— group, or oneor more hydrogen atoms in the alkyl or substituted alkyl are substitutedwith F atom or Cl atom; and wherein a structural formula of the thermalcrosslink material is: